This invention relates in general to the repair of foundation walls and more particularly to a method of strengthening and reinforcing concrete block foundation walls.
The foundation walls of residential buildings are commonly constructed of concrete blocks which are stacked in staggered courses and bound together by mortar. Although concrete block walls are strong in compression, they have little tensile strength and are much more vulnerable to lateral forces than solid concrete foundation walls. For example, when the foundation wall is fully or partially below ground, as is often the case, it is acted upon by the soil which is back filled against the foundation. Considerable lateral forces can be exerted against the wall by expanding soil and also by hydrostatic pressure. It is not uncommon for these forces to cause the foundation wall to bow inwardly and develop cracks, primarily in the horizontal mortar joints which are especially susceptible to damage. In extreme cases, the entire wall can buckle and cause extensive structural damage to the foundation and the overlying building.
In order to overcome this problem, methods have been proposed for strengthening and reinforcing a concrete block foundation wall after the foundation and the overlying building have been constructed. Such methods typically involve the insertion of steel reinforcing rods into the vertical channels or passages that are formed within the wall by the aligned cavities in the individual blocks. During construction, rods can be installed from the top without great difficulty. However, once the building has been completed, it is necessary to open up the wall from the basement side in order to gain access to the passages for installation of the reinforcing rods. As disclosed in U.S. Pat. No. 4,353,194 to Norton, one or more large openings must be formed in the basement wall so that reinforcing bars can be inserted into the interior wall passages. The need to form large openings in the wall requires considerable time and effort, both in chiseling the openings and in repairing them at the end of the procedure. Even more importantly, the relatively large amount of material that is broken away from the blocks during formation of the openings detracts significantly from the overall strength of the wall. Therefore, the formation of large access openings in the wall is highly undesirable and should be avoided if possible.